1. Technical Field of the Invention
The present invention relates to telecommunications networks, and more particularly, to a method for enabling a subscriber selective control of receipt of calls from various roamer ports.
2. Description of Related Art
In the North American Cellular Network (NACN), a mobile subscriber may roam between service areas of competing vendors. Various techniques have been developed to enable a mobile subscriber to continue being provided with mobile telephone services once they have left their home service area. In a first alternative, once a mobile subscriber travels into a new mobile switching center (MSC) coverage area and turns on their mobile station for the first time, the mobile station attempts to register with the servicing MSC for the area by transmitting an associated identification number known as the international mobile subscriber identity (IMSI) number or Mobile Identification Number (MIN). The serving MSC then communicates with the home location register (HLR) associated with the mobile station using the received IMSI/MIN. This communication is to inform the HLR of the mobile station's new location and to receive requisite subscriber information from the HLR necessary to provide mobile services to the newly registering mobile station.
When a call is made to the roaming subscriber, the calling station dials a cellular number associated with the subscriber, and the call is routed to the gateway MSC (GMSC) corresponding to the dialed cellular number. The GMSC queries the HLR of the called subscriber for the roaming location of the called subscriber. The HLR queries the visited MSC where the called subscriber is currently located and requests a temporary location directory number (TLDN) which is returned to the HLR and the GMSC. The GMSC uses the TLDN to route the call to the called subscriber. The calling station will accrue long distance charges for maintaining a connection to the GMSC of the called subscriber. The roaming called subscriber accrues similar charges when the call is routed back to their roaming location. In a situation where the calling station and the called subscriber may be located in the same area, this creates unnecessary expenses.
In order to combat this problem, the concept of the roamer port was developed. The roamer port is a function designed to minimize the long distance charges that a calling station and called subscriber are liable for when the called subscriber is a long distance from his/her GMSC, but a short distance from the calling station. When utilizing a roamer port, a calling station dials a dedicated roamer port telephone number. This connects the calling station to a roamer port that then sends the calling station a dial tone. Upon hearing the dial tone, the calling station dials the subscriber's normal cellular telephone number. The roamer port seizes a signaling trunk to the home location register of the subscriber only for the period of time needed to retrieve a routing number for the subscriber. The signaling trunk with the home location register is then released, and a call is set up from the calling station to the roamer port to the roaming subscriber. Thus, the subscriber station incurs no long distance charges if the roamer port is local but still may incur long distance charges if the roamer port is a long distance from the called subscriber. The calling station only incurs those charges needed to connect to the roamer port.
While the use of roamer ports have enabled cellular service subscribers to limit the long distance costs involved in utilizing roamer functionalities, there still exist the possibility of incurring long distance costs from roamer port calls via a port that is not closely located. Thus, some manner of enabling a subscriber to control from which roamer ports they receive roamer port calls would greatly benefit the subscriber's ability to utilize cellular services in a cost efficient manner.